the enzyme has low affinity for CTP, ATP or thiamine triphosphate. Nucleoside triphosphatase activity is negligible in the presence of 5 mM Mg2+, but a small activity is observed in the presence of 1 mM Mn2+, in particular with GTP. Guanosine 5’-tetraphosphate and long chain polyphosphate (containing about 65 phosphate residues) are not hydrolyzed. The enzyme has no adenylyl cyclase activity

the His-tagged mutant is about 10times less active than the wild type enzyme, but the optimal conditions for activity are essentially the same. The mutant is more strongly activated by Mn2+ than by Mg2+, and the inhibitory effects of Ca2+ and Zn2+ are less pronounced